Improvement in the Decay Resistance of Melia Dubia Wood against White Rot Fungi and Changes in Properties due to Thermo-Hydro-Mechanical Modification

Abstract

Despite extensive studies on thermal modification, limited research has focused on fast-growing, short-rotation species like Melia dubia. While Melia dubia holds significant industrial importance due to its rapid growth and high demand in the pulpwood, plywood, and timber sectors, the juvenile wood produced in short-rotation plantations is often less durable. Thermo hydro mechanical (THM) modification combines thermal and mechanical treatment under controlled conditions, offers a sustainable, eco-friendly alternative to chemical preservative treatments. In the current study, specimens from Melia dubia wood were used to obtain wood material with improved decay resistance by using THM treatment, performed at four temperatures: 160°C, 170°C, 180°C, and 190°C. Fungal resistance was tested under laboratory conditions through a soil block bioassay against white rot fungi Trametes versicolor, which indicated that decay resistance increased with increasing temperature. The highest weight loss was recorded in the untreated control samples, whereas the samples treated at 190°C showed the lowest weight loss percentage, indicating enhanced decay resistance. At the same time, noticeable changes in color, weight loss, and thickness were observed post-treatment. Correlation analysis derived from a scatterplot matrix revealed a positive correlation between temperature and density (r = 0.51), a significant negative correlation between temperature and weight (r = -0.45), and a weak, non-significant negative trend between weight and density (r = -0.14). These findings highlight that higher temperatures increase density while reducing weight and thickness, improving wood durability.

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